1. Field of the Invention
The present invention relates to an intermediate shaft apparatus of a steering shaft assembly which, although compact, is capable of enlarging its contractible range when an impact is applied thereto, and which facilitates the operation of assembling the intermediate shaft apparatus onto relevant components of a vehicle body and is capable of improving the work efficiency.
2. Description of the Related Art
As a general structure of a steering apparatus, a contractible intermediate shaft is provided between a steering wheel shaft and a steering gear box.
As a contracting structure of the intermediate shaft, various structures are known. As a specific example, as disclosed in Japanese Utility Model Application Laid-Open No. 73079/1989, a structure is known in which, in an intermediate shaft having a plurality of shafts arranged in a multi-stage (telescopic) structure in an axial direction, the shafts are arranged to be slidable only in the axial direction, and the respective shafts are fixed to each other by means of injection-molded or resin-molded portions.
When a fixed impact load or more is applied to the intermediate shaft in the axial direction, fixing portions formed of the injection-molded or resin-molded portions are fractured, allowing the intermediate shaft to be contractible in the axial direction.
With the above-described structure, it is possible to obtain a large stroke for absorption of the impact in the intermediate shaft. However, with the above-described intermediate shaft of the multi-stage type, since the respective coupling portions are fixed by the resin-molded portions in advance, the intermediate shaft must be assembled onto joints of a vehicle body in a state in which the distance between the joints for the intermediate shaft is fixed.
For this reason, in a case where the assembling space between the joints of the vehicle body for mounting the intermediate shaft is narrow and does not have leeway, there is a possibility that the assembling efficiency becomes poor and the assembling is made difficult.
Further, in a case where an attempt is made to mount to the contractible intermediate shaft of the above-described multi-stage type in combination with an elastic shaft coupling, since the portion of the elastic shaft coupling is added, the axial length becomes further elongated, which further aggravates the assembling efficiency, or causes the combination with the elastic shaft coupling to be abandoned.